In rotary pumping operations, a downhole pump stator and a downhole pump rotor are positioned within the well tubing. The well tubing is perforated in the vicinity of the rotor and stator allowing the entry of fluid therebetween. Upon rotation of the downhole pump rotor, fluid is carried up the well tubing to the production flow tee. In order to rotate the downhole pump rotor, the rotor is connected by a coupling to a sucker rod. In many installations a plurality of sucker rods are used. The sucker rod is, in turn, connected by a coupling to a polished rod. The polished rod extends through a stuffing box and has mounted on its remote end a drive pulley. The drive pulley engages a belt from a drive motor which imparts a rotational force via the polished rod and sucker rod to the downhole pump rotor.
The primary function of the stuffing box is to prevent a leakage of fluid up past the rotating polished rod. The polished rod is typically between 20 and 40 feet long, only a small portion of which is positioned within the stuffing box. The polished rod is, in turn, connected to at least one sucker rod, which is typically 25 feet long. This combined length of rotating rod unavoidably has eccentric deviations. These eccentric deviations accelerate wear, thereby reducing the useful life of the stuffing box.